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SubjectRe: [RFC Patch] net: reserve ports for applications using fixed port numbers
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David Miller wrote:
> > Octavian Purdila wrote:
> >>
> >> int inet_is_reserved_local_port(int port)
> >> {
> >> if (test_bit(port, reserved_ports))
> >> return 1;
> >> return 0;
> >> }
> >>
> > Above check is exactly what I'm doing in the LSM hook.
>
> But his version can be done inline in 2 or 3 instructions.
>
> An LSM hook will result in an indirect function call,
> all live registers spilled to the stack, then all of
> those reloaded when the function returns.
>
> It will be much more expensive.

If you can accept his version, I want to use his version (with an interface for
updating above "reserved_ports" by not only root user's sysctl() but also MAC's
policy configuration).


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